The present invention claims priority from Japanese Patent Application No. 10-263415 filed Sep. 17, 1998, the contents of which are incorporated herein by reference.
1. Field of the Invention
The present invention is utilized in a printer for a computer, a facsimile or a copier, etc. The present invention relates to an improvement of a structure of an ink jet recording head to be used in an ink jet recorder and a manufacturing method thereof. Particularly, the present invention relates to an improvement of an ink jet recording head having pressure chambers each having a wall surface made of ceramics, for selectively pressurizing ink therein to jet ink droplets through nozzles of the head.
2. Description of Related Art
An ink jet recording head comprises a plurality (n) of nozzles, n discrete pressure chambers provided correspondingly to the respective n nozzles, an actuator for selectively producing mechanical displacement in the discrete pressure chambers and an ink pool for supplying ink to the discrete pressure chambers. The number n of the nozzles may be, for example, 24 or 48. The actuator is driven such that an internal pressure of each discrete pressure chamber corresponding to a nozzle from which ink is to be jetted is pulsated. The n nozzles are usually arranged with an interval of from several millimeters to ten and several millimeters and the ink jet recording head is compact. Therefore, the ink jet recording head must be realized by precise machining.
One example of a conventional ink jet recording head having such structure is disclosed in Japanese Patent Application Laid-open No. Hei 8-58089, in which wall surface portions of discrete pressure chambers are formed of ceramics. With the use of ceramics as the wall surface material of the discrete pressure chambers, an anti-corrosive, ink jet recording head can be realized. Therefore, the life of the ink jet recording head can be elongated. Further, since ceramics material has high rigidity, it is possible to reduce mechanical displacement of a wall surface of each discrete pressure chamber by internal pressure of the discrete pressure chamber, compared with a case where a similar wall structure is realized by adhering plastic material and metal material together. This structure is superior in that an amount of ink to be jetted from a nozzle can be made uniform and that unnecessary pressure propagation (cross-talk) to adjacent discrete pressure chambers is small.
The present inventors had investigated the above mentioned conventional structure disclosed in Japanese Patent Application Laid-open No. Hei 8-58089 and have found that it is impossible to check an interior of each discrete pressure chamber of the disclosed structure during a manufacturing process since sintering of ceramics is performed in a state where the discrete pressure chambers are substantially sealed. That is, when the ceramics sintering process is performed while the discrete pressure chambers are substantially sealed, there may be a case where extraneous substances resulting from such as partial falling of ceramics material are left as they are in the discrete pressure chambers.
Further, there may be a case where a volume of each discrete pressure chamber is occasionally becomes larger or smaller than a standard volume. Since such defect, if any, is found by an operation test of a finished ink jet recording head, the manufacturing yield is degraded, causing the cost of product to be increased.
In the structure in which the discrete pressure chambers are substantially sealed, it is impossible to easily perform a hydrophilic processing and other processing for inner wall surfaces of the discrete pressure chambers. Therefore, it is difficult to obtain a required operation performance of the ink jet recording head and the life of the ink jet recording head is shortened.
The present invention was made in view of the above mentioned difficulty and has an object to provide a structure of an ink jet recording head in which surface portions of walls of an ink pool and discrete pressure chambers can be formed of ceramics to provide superior anti-corrosive characteristics against ink and reduced mechanical displacement of the discrete pressure chambers and interiors of the discrete pressure chambers and the ink pool can be checked during a manufacturing steps and the manufacturing method thereof.
Another object of the invention is to reduce a product cost by improving yield thereof.
Another object of the present invention is to provide a structure of an ink jet recording head having discrete pressure chambers can be performed for interiors of the discrete pressure chambers thereof and a manufacturing method thereof.
A further object of the present invention is to provide a structure of an ink jet recording head in which cross-talk between adjacent discrete pressure chambers is reduced and in which density of discrete pressure chambers can be increased, size can be reduced and nozzles can be increased in number, and a manufacturing method thereof.
In order to achieve the above objects, the manufacturing method of the present invention is featured by that the durability and reliability of an ink jet recording head formed of ceramics are improved and the printing quality is improved. In the present invention, the sintering step is performed while the discrete pressure chambers and the ink pool are open and the discrete pressure chambers are sealed by adhering a vibration plate to the pressure chamber plate after a check step.
That is, a first feature of the present invention is a first method for manufacturing an ink jet recording head having discrete pressure chambers each having a ceramics wall surface, comprising the steps of laminating, on one and the other surfaces of an ink supply plate formed with a plurality of discrete ink supply ports and the corresponding number of nozzle ports, a green sheet for a pressure chamber plate and a green sheet for an ink pool plate, respectively, sintering a lamination resulting from the laminating step and adhering a vibration plate to said pressure chamber plate sintered in the sintering step and a nozzle plate to said sintered pool plate.
The ink supply plate may be made of metal. Alternatively, the ink supply plate may be of ceramics. In the latter case, it may be a green sheet in this stage or a ceramics plate provided by preliminarily sintering the green sheet. The first method may further comprises, between the sintering step and the adhering step, the step of checking wall surfaces of the discrete pressure chambers or the step of performing a hydrophilic processing with respect to the ceramics wall surfaces of the discrete pressure chambers. That is, the discrete pressure chambers after the sintering step are in open state, so that interiors of the discrete pressure chambers can be checked by a microscope, etc., to exclude the ink supply plate having defect, if any. Further, it is possible to perform the ceramics wall surface processing.
It is preferable that the green sheet for the pressure chamber plate is formed with holes corresponding to the discrete pressure chambers before the laminating step and the green sheet for the ink pool plate is formed with a hole corresponding to the ink pool before the laminating step.
In the first manufacturing method, the ink supply plate is prepared first and then a plurality of discrete ink supply ports and the same number of discrete nozzle ports communicated with respective nozzles are formed in the ink supply plate. Thereafter, a green sheet for the discrete pressure chamber plate and a green sheet for the ink pool plate are prepared, holes corresponding to the discrete pressure chambers are formed in the green sheet for the pressure chamber plate and a hole corresponding to the ink pool and holes corresponding to the discrete nozzle ports are formed in the green sheet for the ink pool plate.
The green sheets for the pressure chamber plate having the holes corresponding to the discrete pressure chambers and the ink pool plate having the holes corresponding to the ink pool and the discrete nozzle ports are attached to respective surfaces of the ink supply plate and sintered.
Since, in a lamination resulting from the sintering step, one side of each discrete pressure chamber formed in the green sheet for the pressure chamber plate is open and one side of the ink pool and the discrete nozzle ports formed in the green sheet for the ink pool plate is open, wall surfaces of the discrete pressure chambers, the ink pool and the discrete nozzle ports can be checked in this stage and the hydrophilic processing can be performed for the wall surfaces in this stage. Thereafter, the vibration plate is adhered to the sintered nozzle plate and the nozzle plate is adhered to the ink pool plate.
A second feature of the present invention is a second method for manufacturing an ink jet recording head having discrete pressure chambers each having a ceramics wall surface, comprising the steps of, after the laminating step in the first method and before the sintering step in the first method, forming holes corresponding to the discrete pressure chambers in the green sheet for the pressure chamber plate and forming a hole corresponding to the ink pool in the green sheet for the ink pool plate.
In the second manufacturing method, a green sheet for the pressure chamber plate and a green sheet for the ink pool plate are laminated on one and the other surfaces of the ink supply plate (made of metal or ceramics) formed with the ink supply port and the discrete nozzle ports, respectively, and patterned masks are formed on opposite surfaces of the lamination, respectively. The ink supply plate may be of metal or ceramics. In the case of the ceramics ink supply plate, it may be a green sheet in this stage or a ceramics plate provided by preliminarily sintering the green sheet.
Then, the lamination is sand-blasted through the patterned masks to form the discrete pressure chambers, the ink pool and the discrete nozzle ports and the patterned masks are removed. Thereafter, the lamination is sintered. The pressure chamber plate and the ink pool plate thus formed by the sintering are checked and then subjected to hydrophilic processing. Thereafter, a vibration plate is adhered to the pressure chamber plate and a nozzle plate is adhered to the ink pool plate.
A third feature of the present invention is a third manufacturing method for manufacturing an ink jet recording head having discrete pressure chambers each having a ceramics wall surface, comprising the steps of pattern-printing, on one and the other surfaces of an ink supply plate (3) (made of metal or ceramics) preliminarily formed with a plurality of discrete ink supply ports and the corresponding number of discrete nozzle ports, glass-contained ceramics paste layers, respectively, sintering the ink supply plate and adhering a vibration plate to the sintered pressure chamber plate and a nozzle plate to the ink pool plate.
In the third manufacturing method, the ink supply plate is prepared first and then discrete ink supply ports and the corresponding number of discrete nozzle ports are formed in the ink supply plate. Then, the patterned masks are formed on the respective surfaces of the ink supply plate by laminating glass-contained ceramics paste layers, which become the pressure chamber plate and the ink pool plate, and patterning them. The ink supply plate may be of metal or ceramics. In the latter case, it may be a green sheet in this stage or a ceramics plate provided by preliminarily sintering the green sheet.
Thereafter, the ink supply plate is sintered to form discrete pressure chambers in the pressure chamber plate and the ink pool and the discrete nozzle ports in the glass-contained ceramics paste layer (containing ceramics powder and organic binder) which becomes the ink pool plate. Then, wall surfaces of the discrete pressure chambers, the ink pool and the discrete nozzle ports are checked and then the hydrophilic processing is performed therefor. Thereafter, the vibration plate is adhered to the pressure chamber plate and the nozzle plate is adhered to the ink pool plate.
A fourth feature of the present invention is a fourth manufacturing method for manufacturing an ink jet recording head having discrete pressure chambers each having a ceramics wall surface, comprising the steps of forming, on one and the other surfaces of an ink supply plate formed of metal or ceramics and preliminarily formed with a plurality of discrete ink supply ports and the corresponding number of discrete nozzle ports, photo resist layers, respectively, exposing the photo resist layers with using a mask having a light transparent portion corresponding to holes of a pressure chamber plate and a mask having a light transparent portion corresponding to a hole of a pool plate, respectively, and removing unexposed portions of the ceramics paste layers, filling portions from which the ceramic paste is removed with ceramics paste (containing ceramics powder and organic binder), sintering the ink supply plate prepared in the filling step and adhering a vibration plate to the pressure chamber plate sintered in the sintering step and a nozzle plate to the sintered ink pool plate.
In the fourth manufacturing method, a metal ink supply plate is prepared first and then discrete ink supply ports and discrete nozzle ports are formed in the ink supply plate. Thereafter, photo resist layers in the form of films are formed on respective surfaces of the ink supply plate. Then, the photo resist layers are exposed with using a mask having a light transparent portion corresponding to holes of the pressure chamber plate and a mask having a light transparent portion corresponding to holes of the ink pool and then unexposed portions of the photo resist layers are removed by suitable chemical agent.
Thereafter, the portions from which the unexposed portions of the photo resist layers are removed are filled with ceramics paste and the ink supply plate formed by this filling is sintered. The pressure chamber plate and the ink pool plate thus formed by the sintering are checked and then the hydrophilic processing is performed for them. Then, the vibration plate is adhered to the pressure chamber plate and the nozzle plate is adhered to the ink pool plate.
A fifth feature of the present invention is a fifth manufacturing method for manufacturing an ink jet recording head having discrete pressure chambers each having a ceramics wall surface, comprising the steps of forming, on one and the other surfaces of an ink supply plate formed of metal or ceramics and preliminarily formed with a plurality of discrete ink supply ports and the corresponding number of discrete nozzle ports, glass-contained ceramics paste layers containing photo setting resin, respectively, exposing the photo resist layers with using a mask having a light translucent portion corresponding to holes of a pressure chamber plate and a mask having a light translucent portion corresponding to a hole of a pool plate, respectively, and removing unexposed portions of the ceramics paste layers, sintering the ink supply plate prepared in the removing step and adhering a vibration plate to the pressure chamber plate sintered in the sintering step and a nozzle plate to the sintered ink pool plate.
In the fifth manufacturing method, glass-contained ceramics paste layers (containing ceramics powder and organic binder) containing photo setting resin are formed on both surfaces of an ink supply plate (made of metal or ceramics) preliminarily formed with discrete ink supply ports and discrete nozzle ports. Then, the glass-contained ceramics paste layers are exposed with using a mask having a light translucent portion corresponding to holes of the pressure chamber plate and a mask having a light translucent portion corresponding to holes of the ink pool plate, and unexposed portions of the ceramics paste layers are removed. Thereafter, the ink supply plate formed by removal of the unexposed portions of the ceramics paste layers is sintered. Then, the pressure chamber plate and the ink pool plate formed by the sintering are checked and subjected to hydrophilic processing. Then, the vibration plate is adhered to the pressure chamber plate and the nozzle plate is adhered to the ink pool plate.
A sixth feature of the present invention resides in a structure of an ink jet recording head having discrete pressure chambers each having a ceramics wall surface and manufactured by the above mentioned manufacturing method, in which a pressure chamber plate formed with spaces each having a configuration of a discrete pressure chamber and an ink pool plate formed with a space having a configuration of an ink pool are adhered to one and the other surfaces of an ink supply plate preliminarily formed with a plurality of discrete ink supply ports and a plurality of discrete nozzle ports, respectively, and sintered, and in which a vibration plate is adhered to the pressure chamber plate and a nozzle plate formed with discrete nozzles is adhered to the pool plate. The ink supply plate may be made of metal or ceramics.
Ink is continuously supplied to the ink pool formed in the ink pool plate and ink in the ink pool is supplied to the discrete pressure chambers of the pressure chamber plate through the respective discrete ink supply ports of the ink supply plate. When the vibration plate is driven by the actuator to pressurize the interiors of the discrete pressure chambers, ink in the discrete pressure chambers is jetted from the nozzles provided in the nozzle plate through the discrete nozzle ports formed in the ink supply plate and the ink pool plate. With the ink jet, a printing is performed.
As described hereinbefore, according to the manufacturing method of the present invention, it is possible to precisely form the wall surfaces of the discrete pressure chambers and the ink pool by using ceramics, so that it is possible to maintain the superior characteristics of durability against ink and. reduction of the mechanical displacement of the discrete pressure chambers. Further, it is possible to check the interiors of the discrete pressure chambers and the ink pool during the manufacturing thereof since the sintering is performed with the discrete pressure chambers and the ink pool being open. Therefore, it is possible to exclude ink jet recording heads having defects such as falling-off of the ceramics parts and deformation thereof during sintering before the ink jet recording heads are finished. It is also possible to perform the hydrophilic processing and other processing for the interior of the discrete pressure chambers and the ink pool. Therefore, it is possible to reduce. the cross-talk between the adjacent discrete pressure chambers to thereby improve the yield of products and reduce the product cost. Further, it is possible to increase the density of the discrete pressure chambers, to reduce the size of the head and to increase the number of nozzles.